Soniox vs AssemblyAI speech-to-text

Compare the Soniox and AssemblyAI speech-to-text APIs on your own audio — accuracy, token-level real-time streaming, built-in translation, and pricing.

Soniox vs AssemblyAI pricing, side by side

AssemblyAI and most speech-to-text APIs charge extra for diarization, translation, and multilingual support, so the headline rate hides the real bill. Soniox is one flat rate with all of it included. Set your monthly hours below to calculate your all-in cost per hour and see how Soniox compares to AssemblyAI, side by side.

Pricing calculator

Stop overpaying for speech AI

SonioxvsAssemblyAI

1,000 hours of audio / month

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Pricing assumptions

Based on public pay-as-you-go pricing. Enterprise discounts and committed-use contracts may differ. Some providers charge separately for certain features. The calculator uses the public price for the provider configuration that most closely matches Soniox.

Why pick Soniox over AssemblyAI

stt · accuracy

English

Understand every word, in every language.

Soniox delivers native-speaker accuracy across 60+ languages, even with accents, dialects, noise, or mid-sentence language shifts. Transcripts are production-ready, right out of the box.

AssemblyAI’s accuracy is strongest on clean English audio and can slip on heavy accents and noisy, real-world speech.

stt · streaming

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Real-time that doesn’t cut corners.

With token-level updates in milliseconds, Soniox delivers real-time transcription and translation without sacrificing accuracy. No lag, no jumps, just smooth, natural speech.

Soniox refines token-by-token in real time, with non-final → final markers AssemblyAI’s streaming doesn’t expose.

stt · diarization

Designed for messy, multilingual conversations.

People interrupt, overlap, and code-switch. Soniox automatically handles mixed-language sentences, accents, speaker shifts, and conversation flow.

AssemblyAI’s real-time multilingual covers six languages; Soniox handles mid-conversation shifts across 60+.

stt · context

Built-in domain intelligence.

Soniox adapts to your field – healthcare, finance, law, and more – recognizing terminology and enforcing translations without custom models.

AssemblyAI has no real-time, in-stream translation; Soniox steers vocabulary and translation live.

stt · language switching

Global-ready from the start.

One API handles real-time transcription, any-to-any translation, language detection, speaker separation, and more, in 60+ languages. No stitching services together.

AssemblyAI transcribes 99 languages but has no real-time, in-stream translation — you’d add a separate translation step.

Trusted by teams building global voice products

Developers choose Soniox for global-ready, real-time fluency

AssemblyAI is known for simple APIs, but for speech itself Soniox outperforms, delivering higher accuracy, true real-time streaming, and global coverage in one API.

With Soniox, you can build one app that works for 8 billion people across 60+ languages. Soniox consistently delivers world-class accuracy, faster real-time streaming, speaker detection, and true multilingual coverage.

Cleaner transcripts, zero mistakes

Benchmarks show Soniox at 1.25% WER in English vs 1.74% for AssemblyAI. Less cleanup, more trust.

One API for 60+ languages

Transcription and translation built in, so your app works worldwide without chaining APIs.

Streaming that feels instant

Token-level results in milliseconds make apps fast, fluid, and human — not robotic.

Soniox surpasses AssemblyAI in any language

Get the most accurate, real-time speech-to-text transcription and translation in 60+ languages

Frequently asked questions about Soniox vs AssemblyAI

How accurate is AssemblyAI compared to Soniox?

In 2026 benchmarks, AssemblyAI had an 1.74% WER on English speech, versus 1.25% for Soniox. That means Soniox produces cleaner transcripts with fewer mistakes to fix, especially as audio gets more complex.

Does AssemblyAI support translation?

AssemblyAI offers translation only for pre-recorded audio as a paid add-on — it has no real-time, in-stream translation. Soniox includes two-way real-time translation across 60+ languages in the same API call.

How fast is AssemblyAI's streaming?

AssemblyAI streams in chunks, which can add noticeable lag in live apps. Soniox streams token-by-token in milliseconds, so conversations feel natural and responsive.

What about multilingual or messy audio?

AssemblyAI now offers real-time diarization and endpointing, but as paid add-ons. Soniox includes diarization, endpoint detection, and any-to-any translation by default in one stream, so it works better in real-world, multilingual conversations.

How does AssemblyAI pricing compare to Soniox?

AssemblyAI's lower-end models are roughly similar in price, but Universal-3 Pro streaming with diarization costs nearly 5× more. Soniox stays flat at ~$0.10–0.12/hr with all features included.

Why is Soniox more cost-efficient?

With Soniox, all features are included by default – transcription, translation, diarization, timestamps, and confidence. AssemblyAI prices real-time diarization and translation as separate add-ons, so matching Soniox’s bundled transcription, translation, diarization, timestamps, and confidence costs more.

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